UPDATE in 2013 - I can't believe that I did not post this years ago. I replaced the
module in that 1978 several times, and finally figured out that the cute
CHROME coil that I had bought was NOT for this type ignition - it was
burning out the modules after a short time. I do not see in this article
where I figured that out and reported it. How I found out now that
I had never shared the REAL problem? I was having trouble with my
1973 and an old Glassic buddy, Bill Crozier from Florida, suggested a
coil replacement.

I replaced the coil, and when getting ready to pitch
the old one, I saw that IT had stamped on it: "29770 use with electronic ignition" --
It sounds like it was also the wrong coil, added by someone before me,
since I have points and condenser, which I don't think is "electronic
ignition". It follows that electronic coils might provide less
power, so a regular coil in an electronic ignition would fry the
ignition parts and, an electronic coil in a points ignition would not
give it enough spark. All I know is that BOTH problems were solved
with the correct coil.

BE SURE YOU HAVE THE CORRECT TYPE COIL FOR YOUR IGNITION TYPE.

In 2004 my 1978 phaeton suddenly quit dead on the
road. A check showed no spark coming from the coil, and
no low voltage going into the coil. After a few minutes
at the side of the highway, and jiggling wires, the car
started and ran back to where I was staying. Later that
day it cut out on the highway, and by the time I pulled
over, the car was running again.

Even later that
evening, the car died again as I slowed for a toll booth.
This time it would not start. We towed it to the hotel.
Later that evening, the car did start again.

It appears that the problem was the IGNITION
MODULE, and one clue was the black tar-like
substance that could be seen dribbling down beneath the
module. Although the Mustang manuals say that this is an
uncommon problem, the part was readily available at
Discount Auto Parts. I asked for the part by year and
make, and they gave me a part numbered EL 107
Module. ($16.95)

I bought some electric wire along with the module and
hung the module under the hood to get me home. It appears
that the module was attached from under the dash.
Replacing it will prove challenging.

The module is the Duraspark box. The circle shows where
some "gook" had seeped out the bottom. The new
one showed that the BACK of the box, against the
firewall, is covered with this black - plastic - tar like
substance. Something must have overheated and melted that
insulation.

The left circle is the dribble, and the right circle are
the wires that are part of the module.

The wires that come with the module end in two plugs
(right circle) which plug into two sockets (left circle)
that go toward the coil area. The unit is unplugged in
this picture - both plugs are different, so you can't
plug them in wrong. There are ears on the car end of the
plugs that snap into slots on the module end. The old
ones cam off easily, but when unplugging the new one,
they were tight.

Removing the old module proved too challenging since it
was bolted from inside the car behind the dashboard and
very high up. I took the easy way out and drilled a
couple of holes near each of the two places that the
module was bolted in, and busted the old one out. I then
used those hollow fasteners that you push into the hole
and screw down a bolt and it spreads out behind. I then
noticed the difference between the old module and new
one. The holes were identical, but the old one had a
small ear at the bottom. The firewall bulges there so the
new one would not rest flat.

I took my trusty reciprocating saw and hacked off the the
corner of the bottom flange. I rounded the edges a little
and buffed the whole thing. It fit fine when modified.